Process for closing a container in metal sheet

ABSTRACT

The container has a tubular body having a peripheral lateral wall provided with an upper end portion and a lower end portion defining an upper retention hook and a lower retention hook to which is double-seamed a lower end wall. An upper end wall is conformed to incorporate a peripheral upper skirt presenting an end edge defining an inverted U shaped upper closure hook to be seated onto the upper retention hook sandwiching an elastic sealing element therebetween. The upper closure hook and the upper retention hook and also a portion of the peripheral upper skirt and a confronting region of the upper end portion are deformed for seaming the upper closure hook onto the upper retention hook and to form, respectively, a retention rib and a retention groove which tightly fits the retention rib.

FIELD OF THE INVENTION

The present invention refers to a process to provide the upper closureof a container formed in metal sheet, such as a closed pail or othercontainer comprising a peripheral lateral wall, with a cylindrical formor an inverted and slightly frusto-conical form and presenting an upperend portion and a lower end portion, to which respective end walls areattached.

PRIOR ART

The containers of the type considered herein have their upper and lowerend walls respectively and peripherally double-seamed in the upper endportion and lower end portion of the peripheral lateral wall, the upperend wall being provided with an a generally eccentric opening having acontour substantially smaller than that of the peripheral lateral wall,and with a gripping handle contained in the interior of the axialprojection of the contour of the container, in order to allow the latterto be lifted by the gripping handle attached only to the upper end wall.The opening provided on the upper end wall is configured to define aseat to which is applied a lid generally formed in a plastic material.

Due to the complexity of the double-seaming processes, which require theuse of specific and generally expensive equipment, these double-seamingphases in the manufacture of the container considered herein are rarelycarried out in the product filling facilities. Thus, the containers areclosed in the manufacturer's facilities, by double-seaming the end wallsto the peripheral lateral wall of the container, being then shipped tothe facilities for filling the product to be commercialized. Since thecontainers are shipped with the end walls already double-seamed to theperipheral lateral wall, they cannot be fitted one inside the other,requiring to be arranged side-by-side and stacked in the transportvehicles and also in the storage places, both at the containermanufacturer and at the filling facilities, requiring a physical spacepresenting an undesirable large volume in relation to the mass of thematerial, considerably increasing the shipping and storage costs andrequiring special cares to transport these containers.

Another drawback of these containers supplied to the responsible for thefilling operation with the end walls already attached, generally bydouble-seaming, results from the fact that the filling can be onlycarried out through the opening of reduced dimension provided in theupper end wall. Thus, the time for filling the product is longer thanthat corresponding to the filling carried out without the upper endwall, as it occurs upon filling containers which are superiorly closedby a removable lid and provided with a suspension handle applied to theperipheral lateral wall and not to the lid.

Aiming to overcome the inconveniences cited above, it was proposed aconstructive solution object of the Brazilian patent application PI0804305-1, “CONTAINER IN METAL SHEET”, filed on Oct. 9, 2008 by thepresent applicant. In this prior solution, the upper end wall can beeasily, quickly, reliably and hermetically affixed to the peripherallateral wall of the container by the filler of the product, withoutrequiring double-seaming operations.

According to said prior constructive solution of the same applicant, theupper peripheral edge of the peripheral lateral wall and the outerperipheral edge of the upper wall are conformed to allow them, through asimple and simultaneous deformation operation to be carried out by thefiller, to be reliably and hermetically affixed to each other, generallywith the aid of an elastic sealing element, in the form of a gasketcompressed between the deformed edges of the peripheral lateral wall andthe upper wall.

In the applications in which a high degree of axial retention isrequired between the upper wall, provided with a suspension handle, andthe peripheral lateral wall of the container, the upper end portion ofthe latter and the peripheral upper skirt of the upper end wall areprovided with one or more circumferential ribs and grooves whichcooperate with each other, upon fitting the upper end wall in theinterior of the upper end portion of the peripheral lateral wall.

Although the provision of the circumferential ribs and grooves leads toa substantial increase in the degree of axial retention of the upper endwall, as well as in the degree of hermeticity in said upper closure ofthe container, these ribs and grooves are provided separately in theskirt of the upper end wall and in the peripheral lateral wall of thecontainer, by the manufacturer of the latter, requiring an undesirabledimensional precision in the manufacture of the two parts, in order toallow fitting them at the final closure of the container and obtainingthe desired degrees of axial retention and additional sealing. Thisprior solution, although providing the advantages mentioned in saidprior patent application of the same applicant, has the inconvenience ofrequiring costly manufacturing procedures.

SUMMARY OF THE INVENTION

Due to the inconvenience commented above in relation to the priorsolution, it is an object of the present invention to provide a processfor closing a container in metal sheet, having a peripheral lateralwall, a lower end wall and an upper end wall which is provided with asmall discharge opening and with a suspension handle and which can beeasily, quickly, reliably and hermetically affixed to the peripherallateral wall by the filler of the product to be packaged, withoutrequiring double-seaming operations or costly operations for conformingthe peripheral lateral wall and the upper end wall with reduceddimensional tolerances.

The present process is applied for closing a container in metal sheet,of the type which comprises a tubular body formed by a peripherallateral wall having an upper end portion and a lower end portion, towhich respective upper and lower end walls are attached.

According to the invention, the closing process comprises the steps offorming the tubular body in metal sheet, conforming its upper and lowerend portions, so as to provide them, respectively, with an upperretention hook and with a lower retention hook, the lower retention hookbeing conventionally double-seamed to the lower end wall.

The upper end wall is conformed in metal sheet, so as to present aperipheral upper skirt with its end edge being bent to configure anupper closure hook when the container is superiorly closed, still emptyor already filled with the product.

The upper closure hook and the upper retention hook and also theperipheral upper skirt of the upper end wall and the upper end portionof the peripheral lateral wall are then deformed together, in order toprovide a seaming of said hooks, upon compressing an intermediaryelastic sealing element, and also the formation of at least one outercircumferential retention rib in the peripheral upper skirt and arespective inner circumferential retention groove in the upper endportion of the peripheral lateral wall, tightly fitting the retentionrib.

The closing process proposed by the invention allows the upper end wallto be hermetically and reliably seamed to the tubular body of thecontainer, without requiring the costly and complex operations ofdouble-seaming or previously forming the retention ribs and grooves withexpensive dimensional tolerances which hamper the manufacture and raisethe costs of these containers.

With the proposed process, the containers can be manufactured withoutthe retention ribs and grooves and conveyed to be filled, with the upperend wall still as a separate piece, but with the lower end wall alreadyduly double-seamed to the tubular body.

In the proposed solution, the whole cross section of the still openupper end portion can be used during the filling, reducing the operationtime before the operation of fitting and retaining the respective endwall in the interior of the peripheral lateral wall, by means of simpleand concomitant axial and radial compression operations, to provide thedeformation of both the closure hook and the upper retention hook andthe concomitant formation of the circumferential rib and groove.

In case the peripheral lateral wall is constructed so as to taper fromone end portion to the other, generally from the upper end portion tothe lower end portion, in a continuous or stepped manner, the containerscan be stored and shipped without the upper end wall and in a conditionin which they remain partially fitted one inside the other in stacks,allowing a substantial economy in storage and transportation volumeuntil they are closed at the filling facility and, preferably, after thefilling operation.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described below, with reference to the encloseddrawings, given by way of example of one of the possible embodiments ofthe invention and in which:

FIG. 1 represents a top plan view of the present container, with itsperipheral lateral wall presenting a circular contour;

FIG. 2 represents a partial diametrical sectional view of the container,illustrating the upper end wall and lower end wall affixed to theperipheral lateral wall, said section taken according to line II-II inFIG. 1;

FIG. 3 represents an enlarged exploded detail of the region of FIG. 2which illustrates the fitting of the upper end wall in the upper endportion of the peripheral lateral wall, illustrating the form of thecomponent parts before seating the upper end wall onto the peripherallateral wall;

FIG. 4 represents the same detail of FIG. 3, but illustrating the upperend wall already seated and only provisionally retained to theperipheral lateral wall;

FIG. 5 represents a reduced lateral view of the container represented inFIG. 4 when a seaming device is applied thereto for compressing theclosure hook and the upper retention hook, for forming the axialretention rib and groove.

FIG. 5A represents a view similar to that of FIG. 4, but illustratingthe application of the seaming device to provide the simultaneousdeformation of the closure hook and upper retention hook and of theperipheral upper skirt together with the upper end portion of theperipheral lateral wall, so as to form the circumferential rib andgroove to be tightly fitted together;

FIG. 6 represents a view similar to that of FIG. 5, but illustratingonly the container; and

FIG. 7 represents a partial diametrical sectional view of two containersconstructed according to the present process, deprived of the upper endwall and partially fitted one into the other.

DESCRIPTION OF THE INVENTION

The present closing process is applied to a container formed in metalsheet, usually tinplate, and comprising a tubular body C formed by aperipheral lateral wall 10, with any polygonal cross section, usuallycircular and having an upper end portion 10 a and a lower end portion 10b, in which respective upper end wall 20 and lower end wall 30 areaffixed.

According to the invention, after conforming a metal sheet portion toform the tubular body C, the latter is submitted to an operation forconforming the upper end portion 10 a and lower end portion 10 b of theperipheral lateral wall 10.

The conformation of the upper end portion 10 a is made so as to provide,therein, an upper peripheral edge 10 c which is outwardly and downwardlybent, defining an upper retention hook 11 with a profile in the spaapproximate form of an inverted U.

In the preferred form of the invention, the upper retention hook 11 isconformed to present an inner lateral leg 11 a defined by part of theupper end portion 10 a of the peripheral lateral wall 10, an arched baseleg 11 b and an outer lateral leg 11 c which is convergent in relationto the inner lateral leg 11 a. The conformation of the lower end portion10 b of the peripheral lateral wall 10 is made to provide a lowerperipheral edge 10 d which is outwardly bent to define a lower retentionhook 12 which may present any known prior art configuration to allow thefixation, for example by double-seaming, of the likewise conformedperipheral edge of the lower end wall 30, also in metal sheet and withany conventional construction. The solution used to reliably andhermetically affix the lower end wall 30 to the tubular body C is not aparticular aspect of the present process, which fixation may be carriedout at the manufacturer's facilities by any adequate method.

After conforming the tubular body C and the upper retention hook 11 andthe lower retention hook 12, a peripheral edge of the lower end wall 30is affixed to the tubular body C, generally by double-seaming.

Concomitantly to the formation of the tubular body C and to the closingof its lower end wall 30, a metal sheet portion is conformed to definethe upper end wall comprising a median panel 21, which is optionallyprovided with well known prior art stiffening circumferential ridges,and with a peripheral upper skirt 22, projecting axially outwardly andwhich is configured to be tightly fitted, under interference, in theinterior of the upper end portion 10 a of the peripheral lateral wall10.

The peripheral upper skirt 22 has an end edge 22 c which is, outwardly,downwardly and inwardly bent, so as to define a closure hook 23 with aprofile in the approximate form of an inverted U.

In the preferred and illustrated form, the closure hook 23 is conformedto present an inner lateral portion 23 a, defined by an upper part ofthe peripheral upper skirt 22 of the upper end wall 20, an arched baseportion 23 b and an outer lateral portion 23 c which is convergent inrelation to the inner lateral portion 23 a and which internallyincorporates an end flange 23 d which projects upwardly.

According to the process of the invention, the peripheral upper skirt 22of the upper end wall 20 can be then fitted and seated in the interiorof the upper end portion 10 a of the peripheral lateral wall 10, withthe container being empty or already filled with the product, saidfitting being carried out to seat the closure hook 23 onto the upperretention hook 11, sandwiching an elastic sealing element 40 previouslyprovided between said hooks 23, 11. (See FIGS. 4, 5A and 6).

In the solution illustrated in the drawings, the fitting of the closurehook 23 onto the upper retention hook 11 is made so that the arched baseportion 23 b of the former is seated on the arched base leg 11 b of thelatter, with the elastic sealing element 40, for example a plastisolfilm, being disposed between said arched base portion 23 b and archedbase leg 11 b.

As illustrated, the elastic sealing element 40 is preferably appliedunder the arched base portion 23 b of the closure hook 23, so as to beseated against the arched base leg 11 b of the upper retention hook 11upon fitting and seating the upper end wall 20 in the interior of theupper end portion 10 a of the peripheral lateral wall 10.

The exploded view of FIG. 3 illustrates the form imparted to the partsbefore closing the container. In this stage, the diameter of the freeend edge of the outer lateral leg 11 c of the upper retention hook 11 isslightly smaller than the diameter of the free upper edge of the endflange 23 d which projects upwardly outwardly inclined. Thus, uponseating the upper end wall 20 in the condition illustrated in FIG. 4,both said parts suffer an elastic deformation to allow the end flange 23d to be fitted under the free end edge of the outer lateral leg 11 c ofthe upper retention hook 11.

Being the container ready to be closed, generally after having alreadybeen filled with the product to be packaged, with the upper end wall 20being already fitted and seated in the interior of the upper end portion10 a of the peripheral lateral wall 10, the closure hook 23 and theupper retention hook 11 and also a portion of the peripheral upper skirt22 and a confronting region of the upper end portion 10 a may besubmitted to a joint deformation operation, so as to provide the seamingof the closure hook 23 onto the upper retention hook 11, compressing theelastic sealing element 40 therebetween and further forming at least oneouter circumferential retention rib 24 in the peripheral upper skirt 22and one inner circumferential retention groove 14 in the upper endportion 10 a of the peripheral lateral wall 10, said retention rib 24being tightly fitted in the interior of the retention groove 14,guaranteeing a tight and reliable coupling between the parts of tubularbody C and upper end wall 20, without requiring especial manufacturingcares for allowing the retention rib 24 to perfectly follow the innercontour of the retention groove 14.

The deformation of both the closure hook 23 and the upper retention hook11 is obtained by applying an inward and upward radial force, inopposition to the application of an outward radial force, against theperipheral upper skirt 22 and the upper end portion 10 a of theperipheral lateral wall 10, in order to simultaneously form theretention rib 24 and the retention groove 14.

In the preferred and illustrated construction, the fitting of theclosure hook 23 onto the upper retention hook 11 is made so that thearched base portion 23 b of the closure hook 23 is seated onto thearched base leg 11 b of the upper retention hook 11, the seaming of theclosure hook 23 onto the upper retention hook 11 also being made so asto seat the inner lateral portion 23 a, arched base portion 23 b andouter lateral portion 23 c of the closure hook 23 respectively againstthe inner lateral leg 11 a, arched base leg 11 b and outer lateral leg11 c of the upper retention hook 11, compressing the elastic sealingelement 40 and having the end flange 23 d projecting upwardly to theinterior of the upper retention hook 11, between the outer lateral leg11 b and the inner lateral leg 11 a of the latter.

As illustrated in FIGS. 5 and 5A, the deformations for seaming the hooksand for forming the retention rib 24 and the retention groove 14 can beeasily carried out after the filling of the product, by means of aseaming device 50 which comprises a plurality of outer peripheralfingers 51 and a plurality of inner peripheral fingers 52, said outerperipheral fingers 51 and inner peripheral fingers 52 being configuredto jointly define circular alignments, with a variable diameter as afunction of the operation of the seaming device 50, and to actsimultaneously against the hooks from the outer side of the containerand against the peripheral upper skirt 22, so as to simultaneouslyproduce the seaming deformation of both the upper closure hook 23 andthe upper retention hook 11 and the formation of both the retention rib24 and the retention groove 14. As can be noted in FIG. 5A, the outerperipheral fingers 51 and inner peripheral fingers 52 are configured toimpart, to the respective parts against which they are seated, thedesired conformation to obtain both the seaming of the hooks and thefitting between the peripheral upper skirt 22 and the upper end portion10 a of the peripheral lateral wall 10, guaranteeing a strong axialretention between the upper end wall 20 and the tubular body C of thecontainer, besides establishing a sealing region additionally to thatdefined by the seaming of the closure hook 23 and upper retention hook11, with the provision of the elastic sealing element 40 therebetween.

Further as illustrated, after finishing the deformation of the closurehook 23 and upper retention hook 11, the outer lateral leg 11 c of theupper retention hook 11 and the outer lateral portion 23 c of theclosure hook assume a substantially rectilinear and downwardly andradially inwardly inclined profile, guaranteeing a strong, reliable andtight fixation of the upper end wall 20 to the peripheral lateral wall10.

With the purpose of facilitating the accommodation of the two parts tobe fixed to each other, as well as the operations of plastic deformationof the metal sheet upon the initial and final formation of the twohooks, the inner lateral leg 11 a of the upper retention hook 11 and theinner lateral portion 23 a of the closure hook 23 are initiallyconformed to present a profile that is substantially rectilinear andslightly inclined upwardly and radially outwardly.

According to the illustrated embodiment, the retention rib 24 and theretention groove 14 are constructed so as to present a cross sectionwith the approximate form of a rounded V, in a convex and in a concavearc, respectively.

Depending on the characteristics of the application of the elasticsealing element 40, it may have a portion of its extension penetratingand being compressed between the inner lateral leg 11 a and the innerlateral portion 23 a of the upper retention hook 11 and of the closurehook 23, respectively, as illustrated in FIG. 5.

Considering that the construction of the present container aims atobtaining a closure which is easily executed, but which can comply withthe safety requirements applied to the containers for dangerousproducts, the peripheral lateral wall can be provided with energyabsorbing means by controlled plastic deformation. Thus, the peripherallateral wall 10 can present two regions respectively adjacent to theupper end portion 10 a and lower end portion 10 b, each occupying about10% to 15% of the height of the peripheral lateral wall 10 and conformedin a plurality of circumferential grooves 10 e presenting a profile inthe form of a laid V with a rounded apex. These regions present apleated structure which tends to deform before an undue deformation ofthe container occurs in the regions in which the end walls 20, 30 areaffixed to the peripheral lateral wall 10.

As can be observed in FIGS. 1 and 2, considering that the two upper endwall 20 and lower end wall 30 are affixed, in a non-removable manner, tothe peripheral lateral wall 10, the median panel 21 of the upper endwall 20 is provided with a generally eccentric opening 21 a of smallerdiameter, and with a gripping handle 60 generally positioned in thecentral region of said upper end wall 20, the gripping handle 60 beingintegrally affixed in said upper end wall 20, so as to allow thecontainer, even if filled, to be lifted by said gripping handle 60. Inthis type of construction, the smaller diameter opening 21 a is usuallyclosed by a removable lid; preferably constructed in a plastic materialand which is not illustrated herein, as it forms no part of the presentinvention.

As already previously mentioned and further illustrated in FIG. 7 of theenclosed drawings, the peripheral lateral wall 10 of the container canbe constructed to allow the partial telescopic fitting between twostacked containers. In the illustrated embodiment, the peripherallateral wall 10 has an inverted and slightly frusto-conical form, thesmaller base coinciding with the lower end wall 30 and the larger basebeing preferably situated in a plane axially spaced back in relation tothe mounting plane of the upper end wall 20 and in which the peripherallateral wall 10 is deformed to define an outer circumferentialprojection 19.

With this construction, a container can be telescopically fitted insideanother inferiorly disposed container deprived of the upper end wall,this fitting, as illustrated in FIG. 7, being carried out until theouter circumferential projection 19 is seated onto the free edge of theupper end portion 10 a of the peripheral lateral wall 10 of theinferiorly disposed container, allowing the thus stacked containers tooccupy a total volume substantially inferior to the volume that would beoccupied with the same number of inferiorly and superiorly closedcontainers stacked one on top of the other. With this partial fittingarrangement, the containers can be stored and shipped with a greateconomy in volume and, accordingly, in cost.

While only one embodiment of the invention has been illustrated herein,it should be understood that the present closing process can sufferalterations in the deformation characteristics of the involved parts,without departing from the constructive concept defined in the claimsthat accompany the present specification.

1. A process for closing a container in metal sheet, of the type whichcomprises a tubular body formed by a peripheral lateral wall having anupper end portion and a lower end portion, to which an upper end walland a lower end wall are respectively affixed, characterized in that itcomprises the steps of: conforming a metal sheet portion to define theperipheral lateral wall of the tubular body; conforming the peripherallateral wall so as to provide, in its upper end portion, an upperperipheral edge which is outwardly and downwardly bent, defining anupper retention hook with a profile in the form of an inverted U; and,in its lower end portion, a lower peripheral edge which is bent todefine a lower retention hook; peripherally affixing the lower end wallto the lower retention hook of the tubular body; conforming a metalsheet portion to define an upper end wall having a median panel and aperipheral upper skirt which presents an end edge which is outwardly,downwardly and inwardly bent, so as to define an upper closure hook witha profile in the form of an inverted U; fitting and seating theperipheral upper skirt in the interior of the upper end portion, withthe container being empty or already filled with the product, so as toseat the upper closure hook onto the upper retention hook sandwiching anelastic sealing element previously provided between said hooks; andsubmitting the upper closure hook and the upper retention hook and alsoa portion of the peripheral upper skirt and a confronting region of theupper end portion to a simultaneous deformation operation, in order toseam the upper closure hook onto the upper retention hook, compressingthe elastic sealing element, and to form at least one outercircumferential retention rib in the peripheral upper skirt and acorresponding inner circumferential retention groove in the upper endportion of the peripheral lateral wall, tightly fitting the retentionrib.
 2. The process, as set forth in claim 1, characterized in that theupper retention hook, with the profile in the form of an inverted U, isconformed to present an inner lateral leg defined by part of the upperend portion, an arched base leg and an outer lateral leg which isconvergent in relation to the inner lateral leg, the upper closure hook,with the profile in the form of an inverted U, being conformed topresent an inner lateral portion defined by an upper part of theperipheral upper skirt, an arched base portion and an outer lateralportion which is convergent in relation to the inner lateral portion andinternally incorporating an upwardly projecting end flange the fittingof the upper closure hook onto the upper retention hook being made sothat the arched base portion of the former is seated onto the archedbase leg of the latter, with the elastic sealing element being disposedbetween said arched base portion and arched base leg, and the seaming ofthe upper closure hook onto the upper retention hook being made so as toseat the inner lateral portion, the arched base portion and the outerlateral portion of the upper closure hook respectively against the innerlateral leg, the arched base leg and outer lateral leg of the upperretention hook, compressing the elastic sealing element and having theend flange projecting upwardly to the interior of the upper retentionhook, between the outer lateral leg and the inner lateral leg of thelatter.
 3. The process, as set forth in claim 2, characterized in thatthe deformation of the upper closure hook and upper retention hook isobtained by applying an inward upward radial force, in opposition to theapplication of an outward radial force against the peripheral upperskirt and the upper end portion of the peripheral lateral wall, in orderto simultaneously form the retention rib and the retention groove. 4.The process, as set forth in claim 2, characterized in that the outerlateral leg and the outer lateral portion of the upper retention hookand of the upper closure hook respectively, are substantiallyrectilinear and inclined downwardly and radially inwardly.
 5. Theprocess, as set forth in claim 2, characterized in that the innerlateral leg and the inner lateral portion of the upper retention hookand of the upper closure hook, respectively, are substantiallyrectilinear and slightly inclined upwardly and radially outwardly. 6.The process, as set forth in claim 2, characterized in that the elasticsealing element has a portion of its extension penetrating and beingcompressed between the inner lateral leg and the inner lateral portionof the upper retention hook and the upper closure hook, respectively. 7.The process, as set forth in claim 2, characterized in that theretention rib and the retention groove are formed by deforming the metalsheet of the respective parts and present a cross section with theapproximate form of a rounded V, in a convex arc and a concave arc,respectively.